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Fiber Tasks Preliminary Design Review

December 5, 2001

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CB Main Distribution Frame

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Patch Panels

• Similar to Termination Panel

• Located throughout the Control building

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Phone System

• Two phones per antennas, – Vertex room and Pedestal

• Phone numbers remain with the antenna• Will use the fiber system• Will use COTS hardware

• Responsible for providing the Fiber from the Termination panel to Phone Room

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Battery Backed-upCommunication

• Similar to VLA WYE Monitor

• Un-interruptible power supply

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MCB Network

• Standard Ethernet ( two Fibers )• COTS Network Router• 1 Gbit/s to antennas• 100 Mbit/s in the antennas• Support ~48 nodes in each antenna

– Two multi-mode fibers per node

– Fiber to the Module

• Patch Panel will be located in the computer room

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LO System

• Responsible for Lasers, Modulators, Fiber, Circulators, Receivers– Maybe integrated into the LO module– Phase stable system

• LO Patch panel – located in the Electronics Room– Fiber test equipment

• System Self-tests included

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IF System

• Transmitters

• MUX-Fiber-DeMUX components

• Fiber Amplifiers

• Receivers

• Online monitoring

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IF Transmitters

• Twelve Lasers – ITU spacing • Automated Test

– Output Power Measured at Each Laser ( 1% tap)– MCB accessible

• Manual Optical Power Measurements– Can be measured at the MUX output

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IF Patch Panel

• Located in the Correlator room

• Includes De-MUX hardware

• Includes Fiber Amplifiers

• Manual Test Equipment– Full Signal Communication Analyzer

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Rack Mount EDFA

• MCB adjusted Gain of each amplifier

• Also measures in/out optical power

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IF Communication Analyzer

• IF Patch Panel– Manual measurements during reconfiguration

• Complete Diagnostic– Jitter– Q Factor– Noise Margin– Rise / Fall times

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IF System On Board Tests

• Test Patterns Generated at each Transmitter

• Nine Test Patterns– No Sync, alternating 1/0, all Ones, all Zeros– Parity Errors

• MCB controlled

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Proposed Frame Format

• EVLA Memo #33

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Divided Sync Word

• Required to Identify Correct 1/2 Sequence

• 10 Bits long, – 6 bit identify Start-of-Frame– Barker Sequence - equal Ones versus Zeros

• Three Stage Synchronization Process

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Sync Implementation

selector

32 bits

@

250 MHz

64 bitlatch

64 bitlatch

16 bit partioningand re-ordering

multiplexby 5

multiplexby 5

selector

multiplexby 16

16 Format bits@ 62.5 MHz

16 Format bits@ 62.5 MHz

64 bits@ 62.5 MHz

64 bits@ 62.5 MHz

80 bits@ 62.5 MHz

80 bits@ 62.5 MHz

16 bits@ 312.5 MHz

16 bits@ 312.5 MHz

16 bits@ 625 MHz

1 bit@ 10 GHz

160 bit Frames @10 GHz

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Three Stage Synchronization

• Stage 1 - Search bits for frame pattern

• Stage 2 – Monitor for “Correct” sync

• Stage 3 – If two “Bad” frames in a row

or 2-out-of-8 fames are “Bad”

Then Start Search Again

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Timing Signals

• Metaframe Index

• Metaframe Sequence Count

• 1 PPS

• 1 Pulse per 10 seconds

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Data Valid Signal

• Initiated at the antenna– Toggle Switch– MCB controlled

• Passed to correlator

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Check Sum - BER

• Each 19 bits Generate a check Sum

• Provides continuous Bit-Error-Rate Performance Monitoring

• Only odd # of errors per 19 bits Detected

• Flags Correlator when over threshold

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Scrambling

• Frame Synchronous Scrambling– Select pattern is modulo 2 added– Entire frame – except sync bits

• Pattern results in– Equal number of Ones/Zeros providing

• Balance ac content, sufficient transitions• Minimize low frequency content

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Conclusion

• Five systems will be supported

• On Board Tests Incorporated ( MCB)

• Patch Panels will have test equipment

• IF Data Format will support Growth

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Next Topic

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IF Signal Path